Seals for rotatable members

ABSTRACT

A seal for the shaft of a ship comprises a holder for two axially spaced sealing rings one of which first engages the rotatable part and the other is a spare ring which if the ring first engaging the rotatable part becomes defective can, by relative axial movement between the holder and the rotatable part, be moved into sealing relation with the rotatable member.

United States Patent [1 1 Walter et al.

[ 1 Nov. 20, 1973 SEALS FOR ROTATABLE MEMBERS [75] Inventors: Gerhard W.H. Walter; Gunter E.

W. Pietsch, both of Hamburg, Germany [73] Assignee:Howaldtswerke-Deutsche Werft Aktiengesellschaft Hamburg und Kiel,Hamburg, Germany [22] Filed: Feb. 17, 1971 [21] Appl. No: 116,093

[ 30] Foreign Application Priority Data June 10, 1970 Germany P 20 28427.9

[56] References Cited UNITED STATES PATENTS 6/1956 Fletcher 277/34.3 X

2,925,291 2/ 1960 Bygbjerg 277/9 X 2,943,874 7/1960 Valdi ct al.277/34.3 3,166,330 1/1965 Boutros 277/9 X 3,432,172 3/1969 Hendrickson277/11 X 3,434,727 3/ 1969 Kollenberger 277/187 X 3,441,284 8/1969Murray et al 277/9 3,413,008 11/1968 Greiner 277/58 3,514,115 5/1970Gallo 277/9 X 3,563,555 2/1971 Koons 277/9 Primary Examiner-Samuel B.Rothberg Attorney-Stevens, Davis, Miller & Mosher [5 7 ABSTRACT A sealfor the shaft of a ship comprises a holder for two axially spacedsealing rings one of which first engages the rotatable part and theother is a spare ring which if the ring first engaging the rotatablepart becomes defective can, by relative axial movement between theholder and the rotatable part, be moved into sealing relation with therotatable member.

8 Claims, 8 Drawing Figures PMENTEUNUV 20 1975 III 5 OF 6 PATENTEDNOVZOI975 sir/3.33s

SHEET 6 BF 6 SEALS FOR ROTATABLE MEMBERS BACKGROUND OFTHE INVENTIONVarious constructions of seals are known which use sealing rings in theform of sleeves for rotatable parts, particularly for shafts, in whichone or more sealing flanges are each provided with a retaining flangewhich terminates in an annular thickened portion which in each case isreceived in a recess provided in a stationary part of the casing andadapted to the cross-section of the annular thickened portion. Sealsutilising such sealing rings have been proposed usually for sealingships shafts, as so-called stern tube seals, that is to say for use atthose points where the propeller shaft projects into the interior of theship or passes out of the hull, said shaft carrying at its outer end theships propeller or screw. In seals of this kind it is also known toprovide an inner seal and an outer seal, each of which may have aplurality of axially spaced sealing rings of the kind referred to above.

Since seals of this kind are usually disposed at points to which accessis difficult, in the event of the failure of the seal, for examplethrough excessive wear of one or more sealing rings, it is difficult toreplace it, and replacement necessitates considerable expenditure ,oftime and labor, since a number of components for such seals must beremoved before access can be gained to the sealing rings. Moreover, itis comparatively complicated for sealing rings of one-piece constructiontobe fitted to shafts when replacement is required.

It is a main object of the invention to provide a seal for a rotatablepart, particularly for a shaft such as a ship's shaft, which in theevent of the failure or wearing out of one or more of the sealing ringsacting on the rotatable part can be rendered effective in a simplemanher.

A further object of the invention is to provide a seal for sealingshafts, particularly ships shafts (stern tube seal) which in the eventof faults occurring or in the event of the failure of one sealing ringor set of sealing rings can be simply and quickly manipulated to renderthe seal effective without the necessity of dismantling and removing thedefective seaing ring or rings.

SUMMARY According to the invention there is provided a seal for arotatable part, particularly for a ship's shaft, comprising at least onefirst sealing ring carried by a holder for initial co-operation with therotatable part and at least one spare sealing ring carried by the holderin axially spaced relation with the first sealing ring or rings forco-operation with the rotatable part on a relative axial displacementbetween the rotatable part and the holder.

As will be hereinafter described the spare sealing ring or rings can bebrought into the working position or positions thereof by a relativeaxial displacement between the rotatable part and the sealing ringholder in various ways.

The preferred field of application of the invention relates to seals forships shafts, access to which is well known to be comparativelydifficult and the repair of which, particularly during travel, isextremely difficult if not impossible. The invention can beadvantageously applied particularly to stem tube seals, both in the caseof external stern tube seals and in the case of internal stern tubeseals.

The particular advantage achieved throughthe invention consists, amongother things,in that in the event of the failure of one or more sealingrings in seals, particularly for ships shafts or propeller shafts, it ispossible by a simple manipulation and without difficulty or loss of timeto restore the original sealing action of the seal without anyreplacement parts being required.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partial section of a shipsstern tube seal with a bush disposed on a propeller shaft and, in itsnormal position, a sealing ring holder provided with a spare seal andadapted to slide relative to the shaft or bush,

FIG. 2 is a partial section similar to that of FIG. 1 but with thesealing ring holder displaced relative to the bush or shaft,

FIG. 3 is a partial cross-section of a modified form of constructionwith, in the normal position, a bush mounted for sliding relative to thestationary seal, and with a spare seal,

- FIG. 4 is a view similar to that of FIG. 3, in which however the bushor the shaft and the bush is or are displaced relative to the stationaryseal holder and the spare seal is situated in the working position,

FIG. 5 shows another embodiment of the invention with a stationarysealing ring holder and a bush adapted to slide relative to the-holderor to its sealing ring, with an alternating arrangement of the sparesealing ring and working sealing ring, in the working position,

FIG. 6 is a section view corresponding to FIG. 5, but with a bush orbush and shaft displaced, the spare sealing rings being situated in theworking position, and

FIG. 7 shows part of a ships shaft or shafting and a propeller shaftwith a spacer between their connecting flanges.

FIG. 8 is a sectional view similar to FIG. 6, additionally showing theships shaft, propeller shaft and spacer, as shown in FIG. 7.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments illustrated inthe drawings relate particularly to ships stern tube seals which areknown in themselves and which for example comprise an outer and an innerstern tube seal with one or more sealing rings. Since seals of this kindare known, this type of seal will be explained only to the extentnecessary for understanding the invention.

In the embodiment illustrated in FIG. 1 a sealing ring holder 8 isprovided with annular flange parts 9,10 and 11, between which there aredisposed a first sealing ring 12, which initially acts on the rotatablepart, and a spare sealing ring 13. As illustrated in the drawing thesealing rings are in the form of sleeve rings, a pointed bearing surfaceof which rests under tension on the rotatable part, the necessarybearing pressure being established by annular coil springs S. A holdingflange formed integrally with the actual sealing ring adjoins the latterand ends in a thickened ring which is mounted without tension in twoholder parts. For this purpose semi-circular recesses, in which thethickened rings of the sleeve sealing rings are received withouttension, are formed in each holder part, or in correspondingintermediate parts. In the working position the holder parts surroundingthe thickened ring abut directly against one another and are detachablymade fast to one another,'for example by threaded bolts. Mounting thethickened rings of the sleeve sealing rings without tension providestheadvantage that no bending forces are transmitted to the holdingflange and thus to the actual sealing ring. The sealing ring holder isfastened to a stationary part by means of threaded bolts 14, of whichonly one is shown in the drawing. The bolts 14 pass through lugs 18carried by the holder part 9 and between the outer side of the lug andthe head of the bolt there is disposed a spacer member 16, which forexample may in each case have the form of 'a U. In the normal workingposition the seal 12 acts as illustrated in FIG. 1 on the rotatablepart, which here is a bush 17.

If the first sealing ring 12 (or a plurality of sealing rings) shouldfail, the connection between the stationary part 15 and the sealing ringholder 8 is released by unscrewing the bolt 14 and, as shown in FIG. 2,locating the spacer member 16 between the lug 18 and the stationary part15, so that the sealing ring holder together with the sealing ring isdisplaced axially along the rotatable part 17 a distance correspondingto the width of the spacer member 16. In this position the spare sealingring 13 acts on the bush 17.

In order to facilitate the sliding of the spare sealing ring 13 over thebush 17, the end face of the bush 17 may be chamfered, as indicated at19. The seal is then ready for use again.

In order to avoid displacement of the sealing ring holder, which isotherwise stationary, together with one or more sealing rings and one ormore spare sealing rings, it is possible, as can be seen from theembodiment illustrated in FIGS. 3 and 4, for the rotatable part 20, forexample in the form of a bush, to be made axially slidable in relationto a stationary sealing ring holder 21, a sealing ring 22, and a sparesealing ring 23. In the embodiment illustrated the bush 20 is for thispurpose disposed for sliding on the shaft, for example the propellershaft of a ship, and for this purpose a diagrammatically indicatedadjusting ring 24 is provided, which acts on a flange 25 on the bush 20.When required, the adjusting ring 24 is detached from the rotat- 7provided on the bush 20.

In the modified embodiment illustrated in FIGS. 5 and 6 a stationarysealing ring holder 27 is provided, which alternately carries sealingrings 28 and 29 and spare sealing rings 30 and 31. In the case of thisembodiment the rotatable part is once again shown as a bush 32 on ashaft. In order to prevent the spare sealing ring or rings from actingdirectly on the rotatable part 32 when in its or their inoperativeposition, a recess 33 is provided on the bush 32 and one spare sealingring 30 is disposed above said recess. In order to facilitate therunning-up of the spare sealing ring or rings the recess or recesses 33are provided with chamfers widening it obliquely outwards. FIG. 5 showsthe seal in the normal working position, while FIG. 6 illustrates theworking position of the spare sealing rings, iriwhich the spare sealingrings 30 and 31 act onthe periphery of the rotatable part (bush 32),while the working sealing rings 28 and 29 previously used are engaged inthe re cesses 33 but are disposed at a distance from the bottom of thelatter. 7 i v f FIG. 7 indicates the possibility of displacing a shaft,for example the propeller shaft of a ship, ,relative to the actual ship5 shaft, a bush being disposed on thelprope ller shaft if desired. Theships shaft is designated 34, its connecting flange 35, the propellershaft 36, and its flange 37. Between the flanges35 and 37, of the twoshafts there is disposed a spacer member 38, which has a widthcorresponding to the length of the sliding movement of the shaft 36together with its bush in relation to the stationary seal or stationaryseals (The seals themselves are not shown).

In the event of the failure of one or more sealing rings, the flanges 35and 37 are released, the spacer member 38 taken out, and the shaft 36moved a certain distance (to the left in the drawing), and theconnection is restored (top half of FIG. 7). The spare sealing ring orspare sealing rings then acts or act on the shaft 36 or on the bush,which was displaced with it, in the working position. I

The elements of FIGS. 5-7 are shown in combination in FIG. 8.

In all embodiments it is possible, by suitable selection of the spacermember 16 according to FIG. 1, or the width of the spacer member 38between the two shafts, or the length of the sliding movement of thebush on the shaft, to give the spare sealing ring or rings a positionrelative to the working sealing rings such that they now act on theshaft or bush in a different position from the point at which thesealing ring or rings acted previously.

We Claim:

1. A seal for a rotatable shaft, comprising:

a plurality of radial lip sealing rings coaxially arranged on a carrierin spaced relationship with one another,

a shaft extending through said rings and carrier, coaxial to said rings,said carrier and shaft being axially displaceablerelation to each other,

said shaft including a bushing portion wherein the axial portion of saidbushing portion opposite at least one of said sealing rings has asmaller diameter than a diameter which can be effectively sealed by saidrings, said one ring being in an inoperative position with respect tosaid bushing portion, and

wherein the axial portion of said bushing portion opposite at least oneother of said sealing rings has a larger diameter which-can beeffectively sealed by said sealing rings, said other ring being in anoperative position with respect to said bushing portion of said shaft.

. .2. The seal of claim 1 wherein said bushing portion is a bushingsleeve separate from but attached to said shaft.

3. The seal of claim 1 additionally comprising means for axiallydisplacing said carrier with respect to said shaft.

4. The seal of claim 3, wherein said displacing means comprises a spacerfor mounting between the carrier and the mount to which said carrier isattached.

concentric to a smaller diameter axial portion of said bushing portion.

8. The seal of claim 3, comprising at least one operative sealing ringand at least one inoperative spare sealing ring arranged at a fixedspacing from one another, and said displacing means has an axialdisplacement length which is ditferent from the spacing between saidoperative and spare sealing rings.

1. A seal for a rotatable shaft, comprising: a plurality of radial lipsealing rings coaxially arranged on a carrier in spaced relationshipwith one another, a shaft extending through said rings and carrier,coaxial to said rings, said carrier and shaft being axially displaceablerelation to each other, said shaft including a bushing portion whereinthe axial portion of said bushing portion opposite at least one of saidsealing rings has a smaller diameter than a diameter which can beeffectively sealed by said rings, said one ring being in an inoperativeposition with respect to said bushing portion, and wherein the axialportion of said bushing portion opposite at least one other of saidsealing rings has a larger diameter which can be effectively sealed bysaid sealing rings, said other ring being in an operative position withrespect to said bushing portion of said shaft.
 2. The seal of claim 1wherein said bushing portion is a bushing sleeve separate from butattached to said shaft.
 3. The seal of claim 1 additionally comprisingmeans for axially displacing said carrier with respect to said shaft. 4.The seal of claim 3, wherein said displacing means comprises a spacerfor mounting between the carrier and the mount to which said carrier isattached.
 5. The seal of claim 3, wherein said shaft comprises twoco-axially connected longitudinal sections, and said displacing meanscomprises a spacer for mounting between the two shaft sections.
 6. Theseal of claim 1, wherein the surface of the bushing portion of the shaftis chamfered between the smaller diameter and larger diameter axialportions.
 7. The seal of claim 1, wherein said carrier carries at leastone spare sealing ring between two other sealing rings, said sparesealing ring in an inoperative position concentric to a smaller diameteraxial portion of said bushing portion.
 8. The seal of claim 3,comprising at least one operative sealing ring and at least oneinoperative spare sealing ring arranged at a fixed spacing from oneanother, and said displacing means has an axial displacement lengthwhich is different from the spacing between said operative and sparesealing rings.